The invention concerns a process for the preparation of organic solutions and in particular solutions containing a quaternary cation and an anion from a deprotonated hydroxy.
A process for the preparation of a solution of a quaternary cation and an anion from a deprotonated hydroxy aromatic in an organic solvent by means of a reactive extraction of a quaternary salt in the presence of an aqueous hydroxide solution, a hydroxy aromatic and an organic solvent is disclosed. Also disclosed is a process for the recycling of a quaternary salt phenolate solution from a reaction mixture.
Salts of quaternary cations and anions from deprotonated hydroxy aromatics, particularly quaternary salt phenolate solutions, may be used in a variety of organic reactions as bases, catalysts or reaction components. Since such salts are not commercially available and their educts are relatively expensive, methods of synthesising these salts and of recovering them from reaction mixtures are required.
DE A 19858967 describes a process for preparing liquid formulations of tetrabutyl ammonium phenolate. Phenolic solutions of tetrabutyl ammonium bromide and sodium phenolate are combined, excess phenol is distilled off and sodium bromide removed by filtration.
The disadvantage of this process is firstly that phenol must be distilled off, requiring a considerable amount of energy, and secondly that the sodium bromide, which may occur as a very finely crystalline deposit, may possibly be difficult to isolate. It is therefore desirable to work out a simpler process that requires less equipment. A further object concerns the recovery of quaternary cation phenolate salts from reaction mixtures. The process should therefore also offer the possibility of reprocessing reaction mixtures in such a way that the quaternary cation phenolate solutions may be recycled.
In working on this object a very simple reactive extraction process was found, with which surprisingly an almost quantitative conversion with surprisingly high extraction yields of organic quaternary salt phenolate solutions are produced, even in a single-stage extraction, with no troublesome by-products.
The invention therefore provides a process for the preparation of organic solutions of salts (Qn+)k[(xe2x88x92O)kxe2x80x94R]n from a quaternary cation (Qn+) and a hydroxy aromatic (R1xe2x80x94(OH)k), characterised in that an aqueous solution of a hydroxide Mr+(OHxe2x88x92)r, at least one quaternary salt (Qn+)m[Ymxe2x88x92]n, R1xe2x80x94(OH)k and at least one solvent that is not completely miscible with water are brought into intimate contact and the aqueous phase is then separated off from the organic phase containing (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and optionally R1(OH)k and/or (Qn+)m[Ymxe2x88x92]n.
The invention also provides a process for the recovery of quaternary salts from reaction mixtures and their recycling as organic solutions of mixtures of salts (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n. In the process a mixture that comprise
1. one or more quaternary salts (Qn+)m[Ymxe2x88x92]n 
2. a hydroxy aromatic R1xe2x80x94(OH)k and optionally
3. one or more organic solvents is reacted as follows:
a) an aqueous solution of a hydroxide Mr+(OHxe2x88x92)r and an organic solution containing the quaternary salt (Qn+)m[Ymxe2x88x92]n are brought into intimate contact and the aqueous phase is then separated from the organic phase containing (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n and/or R1xe2x80x94(OH)k.
b) The (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n contained in this organic solution along with the R1(OH)k and/or (Qn+)m[Ymxe2x88x92]n that are optionally present is returned to the reaction after optional additional reprocessing steps.
The present invention also provides a process for the preparation of organic solutions of salts (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Y(1)mxe2x88x92]n from a quaternary cation (Qn+) and a hydroxy aromatic (R1xe2x80x94(OH)k), characterised in that an aqueous solution of a hydroxide Mr+(OHxe2x88x92)r having at least two different quaternary salts (Qn+)m[Y(1)mxe2x88x92]n and (Qn+)p[Y(2)pxe2x88x92]n and at least one solvent that is not completely miscible with water are brought into intimate contact and the aqueous phase is then separated from the organic phase containing (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Y(1)mxe2x88x92]n. (Qn+)m[Y(1)mxe2x88x92]n and (Qn+)p[Y(2)pxe2x88x92]n are two different members of the large number of compounds defined by (Qn+)m[Ymxe2x88x92]n, where m and p are natural numbers which may be the same or different. m is preferably smaller than p. Halide (Xxe2x88x92) and sulfate (SO42xe2x88x92) are a preferred combination of Y(1)mxe2x88x92 and Y(2)pxe2x88x92, where bromide (Brxe2x88x92) and sulfate are particularly preferred.
The quaternary salts used in connection with the present invention are typically compounds having the formula (XRo+)n, whereby X stands for an atom from group Va or VIa, o for a whole number between 0 and 4 and R mutually independently for C6 to C18 aryl, C7 to C18 aralkyl or C1 to C20 alkyl radicals, and n stands for a natural number.
These include ammonium, guanidinium, phosphonium or sulfonium salts substituted with organic radicals, and optionally also mixtures thereof. The letter n stands for a natural number. Oligomers having n greater than 1 may also be used (in which case (nxe2x88x921) R radicals act as bridges between two X), but monomeric ions (n=1) are preferred.
Ammonium, guanidinium, phosphonium, sulfonium and sulfoxonium ions having C6 to C18 aryl, C7 to C18 aralkyl or C1 to C20 alkyl radicals as organic radicals are suitable for use in the process according to the invention. The radicals in each case may be all the same or different and may themselves be substituted. Any two substituent radicals may be replaced by a ring, and mixtures of several quaternary cations may optionally also be used.
The following ions may be listed by way of examples: tetramethyl ammonium, tetra-n-ethyl ammonium, tetra-n-propyl ammonium, tetra-n-butyl ammonium, di-n-decyl dimethyl ammonium, di-n-octadecyl dimethyl ammonium, tri-n-decyl methyl ammonium, N-methyl-N-decyl morpholinium, N-methyl methyl pyrrolidinium, N-(2-hydroxyethyl)-N-ethyl piperidinium, benzyl tributyl ammonium, phenyl trimethyl ammonium, tetraphenyl ammonium, tetramethyl phosphonium, tetra-n-ethyl phosphonium, tetra-n-propyl phosphonium, tetra-n-butyl phosphonium, di-n-decyl dimethyl phosphonium, di-n-octadecyl dimethyl phosphonium, tri-n-decyl methyl phosphonium, benzyl tributyl phosphonium, phenyl trimethyl phosphonium, tetraphenyl phosphonium, hexaethyl guanidinium, tetramethyl bishexyl guanidinium.
Tetraalkyl ammonium ions, tetraaryl ammonium ions, tetraalkyl phosphonium ions, tetraaryl phosphonium ions and hexaalkyl guanidinium ions are preferably used. Tetrabutyl or tetraphenyl ammonium ions or tetrabutyl or tetraphenyl phosphonium ions are particularly preferably used, whereby tetrabutyl ammonium ions or tetraphenyl phosphonium ions are most particularly preferably used.
Halides, nitrates, sulfates, hydrogen sulfates, carbonates, hydrogen carbonates, phosphates, hydrogen phosphates, dihydrogen phosphates, tetrafluoroborates, perchlorates, carboxylates or hexafluorophosphates, for example, may be used as the counter-anion Ymxe2x88x92 of the quaternary cations. The letter m stands for a natural number. Mixtures of different anions are possible. Halides are preferred, particularly preferably bromide.
Hexaalkyl guanidinium halides, tetraalkyl ammonium halides and tetraaryl phosphonium halides are preferred, whereby tetrabutyl ammonium bromide, tetrabutyl ammonium chloride, tetraphenyl phosphonium bromide and tetrabutyl phosphonium bromide are particularly preferred. The amount of such a quaternary salt may be 0.01 to 30 wt. %, for example, relative to the weight of the reaction mixture. This amount is preferably 0.5 to 15 wt. %, particularly preferably 1 to 5 wt. %.
In the aromatic hydroxyl compounds R1xe2x80x94(OH)kR1 stands for an aromatic radical and k for a whole number from 0 to 4. These include monohydroxylated aromatic compounds (k=1), dihydroxylated aromatic compounds (k=2), polyhydroxylated aromatic compounds (2 less than k less than =4) and bisphenols (k=2), which may have 0 to 4 substituents including C1-C18 alkyl or cycloalkyl, C6-C18 aryl, C7-C18 aralkyl, C1-C18 alkoxy, fluorine, chlorine or bromine. The alkyl, aryl and aralkyl substituents may themselves likewise be substituted or may carry functional groups such as ether, thioether, keto, epoxy groups, halogens, heterocyclic rings. Aromatic substituent rings may be annelated or bridged, and several residual radicals may be combined to form cyclic compounds.
Examples are monohydroxyl compounds such as phenol, o-, m- or p-cresol, o-, m- or p-chlorophenol, o-, m- or p-ethyl phenol, o-, m- or p-propyl phenol, o-, m- or p-tert.-butyl phenol, o-, m- or p-isooctyl phenol, o-, m- or p-stearyl phenol, mesitol, o-, m- or p-phenyl phenol, o-, m- or p-cyclohexyl phenol, o-, m- or p-methoxyphenol, 2,6-dimethyl phenol, 2,4-dimethyl phenol, 3,4-dimethyl phenol, 1-naphthol, 2-naphthol or dihydroxyl or polyhydroxyl compounds such as resorcinol and hydroquinone, and bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis-(4-hydroxyphenyl)cyclohexane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane (bisphenol TMC), -bis-(4-hydroxyphenyl)-m-diisopropyl benzene, 6,6xe2x80x2-dihydroxy-3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1xe2x80x2-spiro(bis)indane, 4,4xe2x80x2-dihydroxybiphenyl, or 2,4xe2x80x2-dihydroxybiphenyl.
Mixtures of different aromatic hydroxyl compounds may also be used. Monohydroxyl compounds are preferably used, particularly preferably phenol.
Individual substances or mixtures of substances that are only partially miscible with water and are inert with respect to the substances used are utilized as organic solvents. Solvents having a boiling point of between around 40 and 200xc2x0 C. are preferred. Also preferred are solvents whose dielectric constants are below around 25, particularly preferably solvents having dielectric constants  less than 15. The inert solvent may be contained in the mixture in a proportion of 0 to 99 wt. %, preferably 20 to 98 wt. %, particularly preferably 40 to 98 wt. %, relative to R1xe2x80x94(OH)k. If the amount used is markedly hyperstoichiometric in comparison to the reaction yield, R1xe2x80x94(OH)k may itself be used as a component of a blend of solvents.
Hydrocarbons, halogenated hydrocarbons and aromatic solvents such as chlorobenzene, dichlorobenzene, fluorobenzene, benzene, toluene, the xylenes, anisole, cyclohexane, petroleum ether, methylene chloride, chloroform or 1,2-dichloroethane, dipolar aprotic solvents such as dimethyl acetamide, acetonitrile, N-methyl pyrrolidone, esters, ethers such as dioxan, tetrahydrofuran, t-butyl methyl ether and etherified glycols, for example, may be used as solvents, particularly preferably chlorobenzene.
Mr+(OHxe2x88x92)r stands for one or more hydroxides from group Ia (r=1) or IIa (r=2) of the periodic table. Examples are lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide. Potassium, sodium and calcium hydroxide are preferred, with sodium hydroxide being particularly preferred. Mr+(OHxe2x88x92)r may be added to the extraction mixture as an aqueous solution or suspension, alternatively it may be added as a solid together with water, whereby the former is preferred. A process is preferred in which the aqueous phase has a pH of 7 to 14, particularly preferably a pH of around 9 to 13.5, before the extraction is performed.
Embodiments making use of the parameters, compounds, definitions and explanations that are cited as being preferred, particularly preferred or most particularly preferred are preferred, particularly preferred or most particularly preferred.
The definitions, parameters, compounds and explanations cited above in general terms or in preferential ranges may also however be combined with one another in any way, in other words across the individual ranges and preferential ranges.
The manufacturing process according to the invention for (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n is preferably performed with a molar ratio of [R1xe2x80x94(OH)k]/[Mr+(OHxe2x88x92)r] of greater than around 1.1 [r/k], since surprisingly it was found that a hyperstoichiometric addition of R1xe2x80x94(OH)k has a positive influence on the yield of the reactive extraction. It is particularly preferably performed with a molar ratio of [R1xe2x80x94(OH)k]/[Mr+(OHxe2x88x92)r] of greater than around 3.1 [r/k].
Depending on the requirements of the organic solutions, around 1 to 99.9% of (Qn+)m[Ymxe2x88x92]n may be reacted to (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n. Surprisingly it was found that the unreacted (Qn+)m[Ymxe2x88x92]n may likewise be co-extracted into the organic phase. This may be entirely desirable, for example if (Qn+)m[Ymxe2x88x92]n acts as a phase transfer catalyst or support electrolyte in a subsequent reaction. The invention therefore also provides organic solutions containing both (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n.
Depending on the desired ratio of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n in the organic phase, the ratio of hydroxide Mr+(OHxe2x88x92)r/(Qn+)m[Ymxe2x88x92]n may be around 0.05 [m/r] to 5 [m/r]. If the ratio is increased, the amount of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n that is formed increases, provided that an excess of R1xe2x80x94(OH)k is present. Surprisingly a ratio of around 1 [m/r] is mostly adequate for an almost complete conversion. Higher ratios then lead to a mostly undesirable higher Mr+ content in the organic solution.
High Mr+ contents may be troublesome in industrial processes since the salts containing Mr+ are generally poorly soluble in organic solution and may precipitate out uncontrollably in reactors.
Surprisingly it was found that the Mr+ content of the solutions prepared by the process according to the invention is below around 20 ppm. Solutions having an Mr+ content of below around 10 ppm are preferred, particularly preferably organic solutions having an Mr+ content of below around 5 ppm. Surprisingly, even in cases where the hydroxide is used hyperstoichiometrically, i.e. Mr+(OHxe2x88x92)r/(Qn+)m[Ymxe2x88x92]n greater than around 1 [m/r], no significant amounts of (Mr+)k[(xe2x88x92O)kxe2x80x94R]r are extracted into the organic phase.
After extraction the organic solutions obtained are saturated with water according to their water absorption capacity. If they are to be used in reactions in which water has a disruptive effect, they must be dried before use. The processes known to the person skilled in the art, such as e.g. drying over anhydrous salts, stripping, molecular sieves, azeotropic distillation, may be used.
Organic solutions of (Qn+)k[(xe2x88x92O)kxe2x80x94R]n and (Qn+)m[Ymxe2x88x92]n are required e.g. in the direct carbonylation of phenol with carbon monoxide and oxygen to diphenyl carbonate. The invention therefore provides the use of the organic solutions according to the invention in oxidative carbonylation reactions.
The volume ratios of organic to aqueous phase may be selected within a broad range; for reasons of phase contact and practicality they are not too different; volume ratios of organic to aqueous phase of around 0.01 to 100 are therefore preferred. It has been found that smaller volumes of water have a positive influence on extraction into the organic phase as well as minimising the quantity of waste water. A phase ratio of organic to aqueous phase of around 0.5 to 80 is therefore particularly preferred, most particularly preferably around 2 to 50.
The aqueous phase may contain additional electrolytes, e.g. an alkali or alkaline-earth halide salt. As was surprisingly found, the presence of (Mr+)m(Ymxe2x88x92)r may even have a positive influence on the yield of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n solutions. A preferred variant is therefore performance in the presence of an additional electrolyte, whereby performance in the presence of a metal salt of the anion Ymxe2x88x92 is a particularly preferred variant and performance in the presence of (Mr+)m(Ymxe2x88x92)r a most particularly preferred variant.
In the process according to the invention for the reprocessing and recycling of organic solutions of salts (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n, the commercial availability of e.g. tetrabutyl ammonium bromide may be used for the synthesis of tetrabutyl ammonium phenolate.
In the oxidative direct carbonylation of phenol, tetrabutyl ammonium phenolate for example is used as this phenolate base (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and tetrabutyl ammonium bromide as the quaternary salt (Qn+)m[Ymxe2x88x92]n. Since phenolate is consumed during the reaction, e.g. by the carbon dioxide produced as a by-product, or partial or complete protonation may occur during reprocessing steps, a regeneration of the phenolate base (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n is an important object in this process. A stream formed during reprocessing and generally containing, in addition to other components, unreacted hydroxy aromatic (R1xe2x80x94(OH)k), quaternary bromide (Qn+)m[Ymxe2x88x92]n and a solvent, may be wholly or partially reacted to the quaternary phenolate by the process according to the invention.
The process may be executed in such a way that the stream is divided and only a split stream is wholly or partially reacted for regeneration of the base. Alternatively the entire stream may also be reacted with the quantity of Mr+(OHxe2x88x92)r required for the desired amount of phenolate. Since surprisingly it was found that especially in a hypostoichiometric state, i.e. with ratios of Mr+(OHxe2x88x92)r/(Qn+)m[Ymxe2x88x92]n of below 1 [m/r], the reaction occurs almost quantitatively with the amount of Mr+(OHxe2x88x92)r, the desired amount of quaternary salt phenolate is relatively simple to adjust. The process may then be controlled in such a way that only (Qn+)m[Ymxe2x88x92]n is added in the reaction feed to compensate for the losses and the losses of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n are entirely made up by the reaction according to the invention.
Since after extraction the solutions are saturated with water, it may be useful to dry them in step b) before using them for reactions in which water is disruptive. Other types of reprocessing, such as e.g. removal of the solvent by distillation, isolation of R1xe2x80x94(OH)k, removal of the residual metal content e.g. by ion exchange or precipitation, evaporation, sedimentation or recrystallisation of the (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n salts, may likewise occur before recycling back into the reaction.
In step a) an aqueous phase containing the reacted portion of the Ymxe2x88x92 is accumulated. If this is a valuable anion such as e.g. PF6xe2x88x92 or bromide, it may be useful to recover this anion too, e.g. by precipitation, reaction to volatile species and subsequent distillation, evaporation of the solution or other methods.
If the reaction mixture contains partially water-soluble by-products, the process according to the invention may additionally be useful for depleting these components. Furthermore, metal salts such as may be present as catalyst components in the reaction mixture may be separated off into the aqueous phase during this extraction, allowing them to be recovered, which may be useful for ecological or economic reasons. Precipitation methods may also be used to isolate these metal salts. A considerable number of metal ions are precipitated out as hydroxides under the extraction conditions. Precipitations with Ymxe2x88x92 or, if Ymxe2x88x92 represents anions of polybasic acids, with the Y(m+1)xe2x88x92 or Y(m+2)xe2x88x92 produced by deprotonation thereof (e.g. Ymxe2x88x92=dihydrogen phosphate, m=1, Y(m+1)xe2x88x92=hydrogen phosphate, Y(m+2)xe2x88x92=phosphate), are also possible and are optionally used for isolating metals. The volume ratios of organic to aqueous phase may be selected within a broad range; for reasons of phase contact and practicality they are not too different; volume ratios of organic to aqueous phase of around 0.01 to 100 are therefore preferred. For the cited reasons a phase ratio of organic to aqueous phase of around 0.5 to 80 is preferred, particularly preferably around 2 to 50.
The aqueous phase may contain additional electrolytes, e.g. an alkali or alkaline-earth halide salt. This may have a positive influence on the yield of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n solutions and is therefore a preferred variant. Particularly preferred is the use of (Mr+)m(Ymxe2x88x92)r, which is also formed as a product, as the additional electrolyte. After extraction the aqueous phase is preferably used in part for the extraction feed stream by being recirculated, or the same aqueous phase is continually used, from which only a purge stream containing (Mr+)m(Ymxe2x88x92)r is continually removed and a compensating Mr+(OHxe2x88x92)r stream added. The distribution equilibria of R1(OH)k, (Qn+)m[Ymxe2x88x92]n and (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n are positively influenced by the resulting hold-up of (Mr+)m(Ymxe2x88x92)r in the extraction and losses in the aqueous phase along with the amount of waste water are minimised.
Alternatively the (Mr+)m(Ymxe2x88x92)r formed as a product may be separated off as a solid and discharged if the solubility product is exceeded.
The recovery process according to the invention for (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n is preferably performed with a molar ratio of [R1xe2x80x94(OH)k]/[Mr+(OHxe2x88x92)r] greater than around 1.1 [r/k], since surprisingly it was found that a hyperstoichiometric addition of R1xe2x80x94(OH)k has a positive influence on the yield of the reactive extraction. It is particularly preferably performed with a molar ratio of [R1xe2x80x94(OH)k]/[Mr+(OHxe2x88x92)r] greater than around 3.1 [r/k].
The ratio of hydroxide to quaternary salt Mr+(OHxe2x88x92)r/(Qn+)m[Ymxe2x88x92]n may be around 0.01 [m/r] to 5 [m/r], depending on the desired ratio of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Ymxe2x88x92]n in the organic phase. If the ratio is increased, the amount of (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n that is formed increases, provided that an adequate amount of R1xe2x80x94(OH)k is present. Surprisingly a ratio of around 1 [m/r] is mostly adequate for an almost complete conversion. Ratios of Mr+(OHxe2x88x92)r/(Qn+)m[Ymxe2x88x92]n of around 0.1 [m/r] to 1.5 [m/r] are therefore preferred. Higher ratios then lead to a mostly undesirable higher Mr+ content in the organic solution and to a high loss of R1xe2x80x94(OH)k.
The process requires the presence of R1xe2x80x94(OH)k to form the product; excess R1xe2x80x94(OH)k facilitates the preparation of the solutions. Although the process may be used with a large number of reactions, reactions in which R1xe2x80x94(OH)k is used as educt are preferred. Also preferred are reactions in which the reaction product is an organic ester, e.g. an ester of R1xe2x80x94(OH)k. Esters of carbonic acid with R1xe2x80x94(OH)k, e.g. diphenyl carbonate, are particularly preferred.
Surprisingly it was found for the recovery process according to the invention that the Mr+ content of the solutions prepared by the process according to the invention is below around 20 ppm. Solutions having an Mr+ content below around 10 ppm are preferred, particularly preferably organic solutions having an Mr+ content below around 5 ppm.
The invention thirdly provides a process for the selective preparation of organic solutions of salts (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Y(1)mxe2x88x92]n, since surprisingly it was found that in a mixture of two quaternary salts (Qn+)m[Y(1)mxe2x88x92]n and (Qn+)p[Y(2)pxe2x88x92]n, (Qn+)p[Y(2)pxe2x88x92]n may be reacted very selectively with the hydroxide Mr+(OHxe2x88x92)r. (Qn+)m[Y(1)mxe2x88x92]n and (Qn+)p[Y(2)pxe2x88x92]n are two different elements from the large number of compounds defined by (Qn+)m[Ymxe2x88x92]n, whereby m and p are natural numbers which may be the same or different. m is preferably smaller than p. Halide (Xxe2x88x92) and sulfate (SO42xe2x88x92) are a preferred combination of Y(1)mxe2x88x92 and Y(2)pxe2x88x92, whereby bromide (Brxe2x88x92) and sulfate are particularly preferred.
Depending on the selected stoichiometry of the compounds, organic solutions containing (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n, (Qn+)m[Y(1)mxe2x88x92]n and (Qn+)p[Y(2)pxe2x88x92]n may be prepared, whereby the molar ratio of (Qn+)m[Y(1)mxe2x88x92]n/(Qn+)p[Y(2)pxe2x88x92]n may significantly increase in comparison to the starting ratio. A further option is to prepare solutions displaying virtually no (Qn+)p[Y(2)pxe2x88x92]n and composed only of the quaternary salts (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n and (Qn+)m[Y(1)mxe2x88x92]n. Almost the entire amount of (Qn+)m[Y(1)mxe2x88x92]n that is used may be extracted into the organic phase, or part of the (Qn+)m[Y(1)mxe2x88x92]n may equally be reacted with Mr+(OHxe2x88x92)r to form (Qn+)k[(xe2x88x92O)kxe2x80x94R1]n.
The process for the selective preparation of quaternary salt phenolate may also advantageously be used in the reprocessing of reaction mixtures. In reactions requiring an organically soluble bromide source and phenolate base, for example, the loss of phenolate may be compensated by the process according to the invention. This does not require the use of the expensive bromide as educt; instead a sulfate may additionally be added, which reacts selectively to the phenolate without the loss of significant amounts of the bromide source.
The extractions according to the invention may be performed in a single step, in several steps or continuously. Continuous extraction, e.g. countercurrent extraction, is generally preferred.
The preparation or recovery processes according to the invention are performed at a temperature of xe2x88x9210 to 200xc2x0 C., preferably 10 to 130xc2x0 C., particularly preferably 20 to 90xc2x0 C., and under a pressure of 0.1 to 200 bar, preferably 0.5 to 50 bar, particularly preferably 1 to 10 bar.
Extraction processes may be used for the processes according to the invention such as are described for example in KIRK-OTHMER, Encyclopedia of Chemical Technology, Fourth Edition, Volume 10, 1993, pages 125-181 and in Ullmann""s Encyclopedia of Industrial Chemistry, Fifth Edition, Volume B3, Unit Operations II, 1988, chapter 6, Liquidxe2x80x94liquid extraction, pages 6-1 to 6-61.
Extraction equipment from the following classification groups may be used to perform the processes according to the invention, such as e.g. columns without energy input, columns with pulsed liquid or pulsed baffles, columns with rotating baffles, mixer-settlers, mixing nozzles and settlers as well as centrifugal extractors.
Examples of columns without energy input that include spray columns, packed columns and sieve-plate columns, which differ in the dispersion of the phases.
Examples of columns with pulsed liquid or pulsed baffles that include pulsed sieve-plate columns, pulsed packed columns, with piston pump, with pulsing devices according to Misek or Wepuko, columns with vibrating sieve plates according to Prochazka or Karr.
Examples of columns with rotating baffles that include the rotating disc contactor (RDC), asymmetric rotating disc extractor (ARD), Oldshue-Rushton multiple-mixer column, Kxc3xchni extractor, Scheibel column, SHE extractor and Graesser contactor.
Examples of mixer-settler extractors that include the Davy McKee mixer-settler, Lurgi tower extractor, IMI, General Mills and box-type mixer-settler according to Denver.
Examples of centrifugal extracts that include the Podbielniak centrifugal extractor and the Robatel centrifugal extractor.
The extractors may be operated as single extractors, parallel extractors or as cascades of extractors. If cascades of extractors are used, equipment from one or more classification groups may be operated simultaneously in one cascade. Phase control in a cascade may be performed cocurrently or preferably countercurrently.
It is likewise known to the person skilled in the art that the process depends on the chemical nature of the R1xe2x80x94(OH)k, (Qn+)m[Ymxe2x88x92]n species and of the solvent, and that depending on the distribution coefficient and the desired separation efficiency the extraction must display a suitable number of theoretical separation stages for the specific separation problem and a contact time adjusted to the kinetics of the reactive extraction.
Generally, however, the extraction is preferably performed in a single mixer-settler, since the extraction yield is usually adequate.